Underwater foundation structure and method therefor



June 4, 1963 o. P. THOMPSON ETAL 3,091,937

UNDERWATER FOUNDATION STRUCTURE AND METHOD THEREFOR Original Filed June21, 1954 5 Sheets-Sheet 1 AIR-WATER TO AIR COMPRESSOR E CAPE June 1963D. P. THOMPSON ETAL 3,091,937

UNDERWATER FOUNDATION STRUCTURE AND METHOD THEREFOR Original Filed June21, 1954 5 Sheets-Sheet 2 FIG.4

June 4, 1963 D. P. THOMPSON ETAL 3,0

UNDERWATER FOUNDATION STRUCTURE AND METHOD THEREFOR Original Filed June21, 1954 5 Sheets-Sheet 3 FIG.7

June 4, 1963 D. P. THOMPSON ETAL 3,091,937

UNDERWATER FOUNDATION STRUCTURE AND METHOD THEREFOR Original Filed June21, 1954 5 Sheets-Sheet 4 June 4, 1963 D. P. THOMPSON ETAL 3,0 ,93

UNDERWATER FOUNDATION STRUCTURE AND METHOD THEREFOR Original Filed June21, 1954 5 Sheets-Sheet 5 nnn FIG.13

FIG.15

United States The present invention relates to working platformsestablishable above a body of water, more specifically to methods of andapparatus for establishing such work platforms over a body of water, andhas for an object the establishment of a working platform which may beused for drilling oil and gas wells along the continental shelf wherewater depths of up to about 500 feet may be encountered, the structurebeing arranged for assembly and disassembly at the drilling site bycontrol of the buoyancy and stability of the assembled structurethroughout either the assembly or disassembly steps by regulation of thewater level within a foundation pontoon and support of the structureduring assembly from the top of a guide caisson initially contacting thebottom, and along which said structure is lowered, said pontoon beingadapted to engage the underwater bottom directly or through load-bearingcaissons permanently connected to the underwater bottom, but from whichthe foundation pontoon may be raised.

The present application is a division of application Serial No. 438,132filed June 21, 1954, and issued on May 10, 1960, as Patent No.2,935,854.

While it has been proposed heretofore to construct offshore drillingplatforms, which may be assembled and disassembled over an underwaterdrilling site, such structures have been primarily designed forrelatively shallow bodies of water, such as those encountered in inlandlakes or rivers, or along the near-shore portion of the Gulf of Mexico.In these locations, the depth of water does not ordinarily exceed about50 to 100 feet. Unfortunately, the use of such structures is notapplicable at locations where the depths of water extend from 100 to 500feet, as encountered in the continental shelf along the Pacific Coast.

The problem of establishing a movable structure at such depth isparticularly important where the ocean bottom slopes sharply away fromthe coast line, and where underwater drilling sites only a few miles offthe coast lie beneath a few hundred feet of water. Because theprobability of failure in exploratory drilling at such underwater sitesis greater than the probability of success, it is highly desirable to beable to move the working platform when unsuccessful exploratory drillinghas been completed, rather than to build and abandon a still use fillstructure. Drilling at such sites is necessarily exploratory; that is tosay, the earths surface below the water has not been sufficientlypenetrated to determine the commercial availability of oil or gas.Economical justification of a program to discover petroleum at suchunderwater drilling sites frequently depends upon the ability to moveand re-use, at a number of exploratory sites, the structure supporting aworking platform, wherein the said platform and supporting structure maycost in the range of one to three million dollars. Contributing heavilyto the high cost of an offshore drilling structure is the great expenseinvolved in the labor and marine construction equipment necessary tobuild such as installation. Therefore, the ease with which a structureand platform can be erected or disassembled at a deep water drill sitemay represent a very great financial gain. The

stem:

shorter the time involved in erecting or dismantling a platform andstructure the less is the chance of losing valuable and expensiveconstruction time due to the unpredictable action of weather and waves.

In accordance with the present invention, a method of establishing anunderwater drilling platform above a body of water is provided whereinthe component parts are so arranged that the structure can be readilyassembled and disassembled and is stable throughout its assembly anddisassembly. To this end, there is provided a foundation pontoon,adapted to be floated to the drilling site, said pontoon having acentral opening through which a guide caisson is passed to theunderwater bottom and anchored thereto. The pontoon is then arranged tobe supported from the upper end of the guide caisson, such as by aplurality of lines and winches, and the buoyancy of said pontoondecreased by admitting water to a plurality of buoyancy chamberstherein. A plurality of buoyant and permanently-sealed frameworkassemblies are then erected on said foundation pontoon sequentially,coincident with gradual lowering of the work platform support structurewhich is effected by the winches and lines from the upper end of theguide caisson. The weight of the submerged foundation pontoon iscontrolled as each buoyant framework assembly is added by maintenance ofthe water level in the pontoons buoyancy chambers at substantially aconstant value by supplying compressed air to said buoyancy chambers.The structure is maintained stable during assembly by virtue of thecenter of gravity of the component parts being held below the center ofbuoyancy of the component parts, and by virtue of the overturning momentresistance offered by the guide caisson. The buoyant frameworkassemblies are then added until the entire structure extends to aposition such that a drilling, or work platform may be mounted apredetermined height above the water level. When the foundation pontoonengages underwater bottom, and erection is completed, the buoyancychambers are permitted to flood by release of compressed air from saidchambers.

In accordance with another aspect of the present invention, there isprovided a method of supporting the foundation pontoon on bottom througha plurality of caisson-receiving openings formed around the periphery ofthe foundation pontoon. In carrying out the invention, there is insertedinto each of the openings a sleeve member having a collar-like bearingsurface through which load may be transferred from the bottom of thefoundation pontoon to a foundation caisson embedded in the underwaterbottom. In the preferred method of establishing these load-carryingcaissons on bottom, a caisson tubing is guided through each of saidsleeve members on a caisson follower which extends upwardly through thewaters surface, after the foundation pontoon has been landed on bottom.Said caisson tubing is forced downwardly into the underwater bottom bydriving or excavating with suitable earth-moving means until the lowerend of the caisson tubing engages a suitable depth of earth stratumcapable of supporting the necessary weight, and also until the upper endof the caisson tubing is a suitable distance below the top of the sleevememher. After the foundation caisson has been constructed to its finaldepth, the lower end of the caisson follower is disengaged from theupper end of the caisson tubing and retracted to the top of the sleevemember. Concrete or similar binding and load-carrying material is thenadded to the interior of the caisson tubing until both the caisson andthe sleeve are filled, including the annular the work platform may beaccomplished through successive removal of the work platform and theframework assemblies. By introducing compressed air into the buoyancychambers of the foundation pontoon at a pressure "suficient to displacea predetermined amount of water,

the buoyancy of the entire structure is increased, thereby permittingthe plurality of lines and winches at the upper end of the guide caissonto raise the remaining framework assemblies and the foundation pontoon.The arrangement of the foundation caissons is such that the foundationpontoon may be lifted directely off the individual foundation caissons,which are themselves permitted to remain at the original underwaterdrilling site.

Further objects and advantages of the present invention will becomeapparent from the following detailed description taken in conjunctionwith the accompanying drawings, which form an integral part of thepresent invention.

In the drawings:

FIG. 1 is a schematic representation of the positioning ofa foundationpontoon constructed in accordance with the invention after being floatedto a drilling site.

FIG. 2 is a schematic representation of the method 'of passing the guidecaisson through the foundation pontoon, ultimately extending said guidecaisson to the underwater bottom.

FIG. 3 is a schematic representation showing the guide caisson extendedto the underwater bottom with the foundation pontoon arranged to besupported from the upper end of said guide caisson.

FIG. 4 is a schematic representation of the method of adding eachbuoyant framework assembly to the other buoyant framework assembliesalready assembled on the foundation pontoon.

FIG. 5 is a cross-sectional view particularly illustrating the interiorconstruction of the foundation pontoon, including the various conduitsused in controlling the buoyancy thereof, while the framework assembliesare being positioned sequentially on the pontoon.

FIG. 6 is a schematic representation, illustrating the method ofintroducing and guiding a foundation caisson tubing by means of acaisson follower, through a loadtransmitting sleeve member in thefoundation pontoon, after the structure has been extended to theunderwater bottom with a working platform first erected above the Waterssurface.

FIGS. 7, 8, 9 and 10 are schematic representations of the successivesteps of installing and constructing a foundation caisson in theunderwater bottom.

FIG. ll is a schematic representation of the manner in which thefoundation pontoon may be raised from a load-carrying caisson duringdisassembly of the entire structure.

FIG. 12 is a schematic representation of the completed offshore drillingstructure and work platform with a derrick positioned thereon fordrilling a plurality of wells.

FIG. 13 is a combination plan and cross-sectional view of a preferredform of the foundation pontoon, particularly illustrating the variousopenings for the central guide caisson and the peripherally-locatedfoundation caissons.

FIG. 14 is a cross-sectional view of a preferred form of the guidecaisson, illustrated in the foregoing figures, and particularlyillustrating the'several drilling positions available at the workplatform.

FIG. 15 is a cross-sectional view of an alternative arrangement for aguide caisson, which will allow a plurality of well bores to be drilledthrough the vertical tubular members thereof, and which may besubstituted for the guide caisson illustrated in FIG. 14.

Referring now to the drawings, it will be observed that the variousfigure numbers have been arranged numerically to particularly illustratethe sequence of steps involved in the erection of an underwater drillingplatform above a body of water. As will be described hereinafter,

the disassembly of the platform for movement to a subsequent drillingsitewill be substantially in the reverse order; i.e., with the stepsfollowing the decreasing order of figure numbers.

As an initial step contemplated by the method of the present invention,a foundation pontoon 10 constructed of reinforced concrete or steel isadapted to be towed, while floating, from its construction site to adrilling site. Pontoon 10 is then positioned and stabilized over thedesired drilling site by a plurality of stabilizing pontoons or barges,twoof which have been illustrated and designated as 11 (behind pontoon10) and 12. Anchor pontoons, such as .11, are desirably held in positionby anchor lines, such as those indicated as Y13 and 14. One of theanchor barges, such as 12, may be used as a support for an erectioncrane, indicated generally as 15.

After spotting of foundation pontoon 10 at the desired location, a guidecaisson member 17, including a plurality of segments 16, is introducedthrough a central opening 19 in pontoon 10 and lowered, step by step, asthe segments are assembled, in the manner suggested in FIG. 2.Desirably, a lowering winch arrangement 18, manually or engine operated,is provided adjacent to opening 19 for supporting caisson assembly 17 asit is lowered through pontoon 10. In this way, the lowering of guidecaisson 17 may be controlled directly from foundation pontoon 10,independently of crane 15.

Caisson 17 is thus progressively lowered until the lower end engages theunderwater bottom, as particularly shown in FIG. 3. The lower end of thecaisson '17 is then desirably forced into the underwater bottom byjetting or excavating the unconsolidated ground directly under thecaisson. In some instances, it maybe desirable to add concrete in thelower end of caisson 17 to assure a firm connection between theunderwater bottom and the caisson, but in other foundation strata it maybe unnecessary to do so.

As further illustrated in FIG. 3, guide caisson 17 is then arranged tosupport from its upper end the foundation pontoon, as Well as thesuper-structure which is to be built thereon, through a winch and weightcounter-balancing system. This arrangement includes a pair of cables 20,secured to the upper portion of pontoon 10 adjacent opening 19, a pairof manual or engine'operated winches 21, and weights 22 secured to theopposite ends of cable 20. Each of the pair of cables 20 is preferablyreeved in a manner to reduce the work required of the winches 21. Afterfoundation pontoon 10 has been thus supported from the upper end ofguide caisson 17, the buoyancy tanks or chambers 25 (best seen in FIGS.5 and 13) within pontoon 10 are partially flooded so that the buoyancyof the pontoon assembly becomes slightly negative,

To assist in the explanation of the manner in which the entire structureis maintained in a balanced and stable condition during its erection ordisassembly, a brief description of the internal construction of thefoundation mitting and releasing fluids to and from buoyancy tanks 25 toprevent excessive loads from being exerted on the guide caisson 17, thecables 20, and the winches 21. The crosssectional view of pontoon 10shown in FIG. 5 particularly illustrates this combination of conduits.As there shown, the interior of foundation pontoon 10 comprises aplurality of integrally formed or cast buoyancy tanks, identified as 25.Each of these buoyancy tanks is connected in common with each other.through three systems of conduits which control the water level, controlthe counterbalancing air pressure within the tanks, and measure thepressure or water level in the tanks. The first of these three systemsor conduits is identified as conduit means 27, which is adapted to admitwater to the bottom of each of the buoyancy tanks 25 through at leastone sea valve 28. As shown, all of the bottom openings 29 in chamber 25are connected in common to conduit 27. The second conduit system isarranged to be connected to an air compressor through conduit means 31,so that compressed air may be supplied through openings 33 in the top ofeach buoyancy chamber 25. The purpose of supplying compressed air tochambers 25 in the present arrangement is to permit a portion of eachchamber to remain unfilled with water but yet prevent the hydrostatichead of water from collapsing the pontoon structure when the pontoon isat any depth. By controlling the air pressure Within tank 25 tocounter-balance the hydrostatic head outside of the pontoon, it ispossible to construct pontoon economically of reinforced concrete andthereby obtain the advantages mentioned above. With proper weight con.-siderations, the pontoon may also be constructed of steel.

Control of buoyancy of the structure during assembly on the pontoon, ascontemplated by the present invention, is contributed to, in part, bythe structural elements 35, partially illustrated in FIG. 5, which aresealed at their ends so that each framework assembly 45 is buoyant. Theframework assemblies 45, each having a center portion adapted to engageclosely and slidably guide caisson 17, are then superimposed, one abovethe other, on pontoon 10. However, an important part of the buoyancycontrol is provided by adjustment of air pressure in tanks 25 tomaintain the depth of water therein at a desired level as the buoyantframework assemblies 45 are added to pontoon 10. In the arrangementshown in FIG. 5, this control is provided by the signal conduit means37, which serves as an air-water escape line. The openings to line 37 inbuoyancy chambers 25 are positioned at a predetermina-ble level so thatthe total weight of water in all of the buoyancy tanks, together withthe weight of the foundation pontoon 10, may be maintained just slightlygreater than, or equal to, the neutral buoyancy of the foundationpontoon 10 when submerged.

By control of valve 46 in air-water escape line 37, there is thenprovided a visible or audible signal as to the maintenance of thisdesired Water level. Hence, the buoyancy of the structure duringerection of a plural ity of buoyant framework assemblies, of whichelements 35 are a portion, will be indicated by the return of either airor water, depending on the location of the water level within tanks 25.When the .water level is at its proper height, there will be a how ofcompressed air through ports 41 in chambers 25, through conduit means 37exhausting through valve 40, which may either be visually indicated oraudibly detected. When the water level rises above ports 41 in tanks 25,water will be forced to rise to the surface and block the return of air.

From the foregoing description of the method of maintaining control ofthe buoyancy of the structure during assembly or disassembly, it will beunderstood that the framework assembly, such as the one being lowered bycrane and identified as 45 in FIG. 4, are prefabricated of tubularmembers 35 and 35A so that they may be placed sequentially and securedone above the other in the assembly process. The members 35 and 35A maybe braced by temporary cross-members 46 during such assembly. Asmentioned above, each of framework assemblies 45 is constructed with themajority of the individual structural members 35 sealed, so that theelements themselves have a positive buoyancy and give to frameworkassembly 45 a positive buoyancy. When combined with pontoon 10, thepartially-completed structure is preferably arranged to have a neutralor a slightly negative buoyancy. Final control of the assembly iscarefully balanced and regulated so that the unbalanced downward load iscounterbalanced by the cables 20, winches 21 and weights 22 actingthrough the top of guide caisson 17, as shown in FIG. 3. The verticalsegments in adjacent assemblies are preferably bolted together (notshown) so that they may be readily assembled or disassembled. Some ofthe vertical columns 35A of the framework assemblies may be so arrangedon the foundation pontoon 10 to permit drilling of wells therethrough,as will be described hereinafter.

Super-positioning of the plurality of the framework assemblies is thencontinued until the foundation pontoon rests on bottom, and theremainder of the structure extends through the body of water to providean upwardlyextending section upon which is mounted first a work platform47. This arrangement is particularly illustrated in FIG. 6. At thispoint in the construction of the platform, the entire structure isleveled if necessary by the insertion of jacking piles 48 throughopenings 49. By means of these jacking piles, the pontoon may be raisedor lowered to plumb the structure prior to the insertion of thefoundation-support caissons through openings 51 in pontoon 10. Incertain cases, where the underwater bottom is sufiiciently consolidatedand leveled, it is possible for the foundation pontoon to serve alone asthe load-supporting member for the entire structure including drillingplatform 70, the derrick 71 and the weight of drill pipe, mud and otherequipment and materials necessary for the drilling of a deep well.

In accordance with another aspect of the present invention, where theunderwater bottom is unconsolidated, a unique method is provided forsupporting foundation pontoon 10 on a plurality of foundation caissons.The construction of these foundation caissons is particularlyillustrated, both as to their method of construction and their completedstructures, in FIGS. 7 to 11, inclusive.

In accordance [with the present invention, a sleeve member designated as50, is inserted and temporarily secured withinfoundation-caisson-receiving openings 51 in foundation pontoon 10.Sleeve member 50 desirably extends through openings 51 with the lowerend thereof having a support collar 52 through which the load offoundation pontoon =10 may be transferred to sleeve 50. While notillustrated in detail, the sleeve 50 as mentioned above is temporarilysupported by the upper end of pontoon 10 within the opening 51, forexample by a remotely-removable pin through sleeve 50, during the timethe pontoon is being lowered to bottom. Alternatively, collar 52 may beprovided with a buoyancy chamber to support sleeve member 50' againstthe bottom of pontoon 10. The construction of sleeve 50 and its positionwithin openings 51 is particularly illustrated in FIG. 7.

As shown in FIGS. 6 and 8, a caisson pipe 55 is adapted to be insertedthrough sleeve 50 and the lower end brought into engagement with theunder-water bottom directly below collar 52. Caisson 55, as furthershown in FIG. 6, is desirably lowered into the positions shown in FIGS.8, 9 and 10 by a caisson follower, designated as 57, which extends fromthe top of caisson tubing 55 to a position well above the rwaterssurface. Guide rails, designated as 62, direct the caisson follower 57and the caisson tubing '55 to pass through the sleeves 50. Caissontubing 55 and follower 57 may be assembled in sections, as shown in FIG.6, with the follower being supported by winches through lines 64. Thus,the caisson and caisson follower may be used as a guide tubing for thefurther construction of the foundation caisson.

As schematically represented in FIG. 9, the interior of caisson tubing55 is excavated by any suitable means, such as by dredging withorange-peel bucket 59. Alternatively, the interior of the caisson 55 maybe jetted or driven into the bottom and the excess soil material withinthe caisson tubing 55 removed hydraulically or by bucket excavators.After caisson tubing 55 has attained a depth suilicient to insureadequate bearing strengths in the soil, caisson follower 57 isdisengaged from caisson tubing '55, for example byrelease of a'pluralityof pivoted hooks 60' schematically indicated in FIG. 9, which are usedtemporarily to hold caisson 55 on follower 57.

As indicated in FIG. 10, the caisson shell 55 is desirably terminated atits upper end within the lengthrof sleeve 50 so that a bond may beeffected between sleeve 50 and caisson shell '55 by the introduction ofsealing material, such as grout or concrete, which is added to fill notonly the length of caisson 55 but also to extend upwardly into the upperportion of sleeve 50. Therfilling of sleeve 50 is then continued untilthe annular space indicated as 61, between sleeve 50 and caisson 55, isalso full of the sealing material. Thus, there is provided a bondbetween the outer surface of caisson 55 and the inner portion of sleeve50. Reinforcing steel cages (not shown) may be formed within thecaisson, if desired, to increase the load-carrying capacity thereof.

Anchor eyes 64 may be forced into the caisson concrete before it hasset, to which tie rods 65 extending to the surface, may be attached asshown in FIG. 11 to control the assent of the pontoon duringdisassembly. With the caisson constructed inaccordance with FIGS. 7 to10, inclusive, there is obtained a complete foundation caissonidentified as 63 in FIG. 11. FIG. 11 also has been used to indicate thatthe foundation caissons are intended to be left at the original drillingsite when the foundation pontoon ltlis raised during disassembly of thedrilling structure. Thus, it will be seen that caissons 63 providefoundation supports for the entire drilling structure which may beintimately incorporated in the underwater bottom to provide adequatebearing support for the drilling structure, but, which do not requirethat the drilling structure be permanently secured to the foundationbed. Accordingly, it will be seen that the foundation caisson structureis an important feature in the provision of a portable drillingstructure of the type eontemplated for use in relatively deep water.

FIG. 12 shows the completed drilling structure with the foundationcaissons 63 in a completed state for supporting the foundation pontoonon bottom. As contem plated in the present invention, a drillingplatform 70 is adapted to support a derrick 71 directly thereon, whichis positioned above the ,work platform 47 at a suflicient height toprevent waves, even under storm conditions, from sweeping over the topof the drilling deck.

FIG. 14 particularly illustrates the preferred inner construction ofcylindrical caisson 17, shown in FIGS. 1 to 12. As seen in FIG. 14, aplurality of stiffener pipes 75 are arranged around the outer peripheryof caisson 17 and extend throughout the length thereof. Conduits 75 areuseful, not only as stiffening members for the column, but alsoas guidesthrough which individual well bores may be drilled into the underwaterbottom. The arrangement is particularly useful where a number of wellsare to be drilled from the platform and deflected outwardly in themanner indicated by bores 85 in FIG. 12.;

While guide caisson 17 has been illustrated in FIGS. 1 to 12, inclusive,as a substantially cylindrical member, this member may be formed from aplurality of spaced tubes of smaller diameter, and interconnected toform a braced, open-framed column. FIG. 15 illustrates such anarrangement wherein a hexagonal pattern of guide columns 75A may besuitably welded together in a structural framework pattern bycross-braces 79. Preferably, each of the six outer guide columns 75A iswelded to a central guide column 75B to form thecompleted guide caisson17A. With the arrangement of FIG. 15 being utilized as a guide column,opening 19, through the central portion of foundation pontoon. 10, maybe suitably modified to engage closely the outer circumference of guidecaisson 17A. Other configurations, such as rectangular, square or otherpolygon-a1 arrangements of the vertical caisson members, may also beused.

Among. the.v modifications which may be made in v the apparatus and themethod of constructing the drilling platform, it will be appreciatedthat control of the weight of the foundation pontoon 10 and the buoyantframework assemblies 45 may be modified by the provision of additionallevel-controlling means in the buoyancy tanks 25' of pontoon 10. Thiscontrol may be provided by the addition of conduits in the buoyancychambers 25 at different levels and suitable valve means for controllingthe fiow of water into and out of the tanks. Thus, the level or depth ofwater in the buoyancy tanks may be controlled, if desired, so that theframework assemblies effectively control the depth at which thestructure floats in the water.

Disassembly of the completed drilling structure, for removal to anotherdrilling site, as mentioned above, will in general be in the reversesequence of steps to those specified for its construction. However,where oceanographic conditions permit, pontoon 10 with one or more ofthe framework assemblies mounted thereon may be moved as a body to thenew location. Likewise, in the initial establishment of the structure, asub-assembly of the complete structure may be made on land or near shoreand then towed to the desired location.

When drilling has been successfully completed into a petroleum-bearingformation from the drilling structure, the pontoon, which may haveoverall dimensions on the order of feet by 100 feet and a height of 15or 20 feet, may be used as storage tankage for the crude petroleum, bydisplacement of ballast water from buoyancy tanks 25.

While various modifications and changes in the method of constructing ordissassembling the underwater drilling platform at its originallocation, as well as in the exact construction of the various unitscomprising that structure, will occur to those skilled in the art, allsuch modifications and changes which fall within the scope of theappended claims are intended to be included therein.

We claim:

1. The method of detachably supporting a foundation pontoon for a workplatform positioned above a body of water which comprises the steps ofdetachably supporting a sleeve member within caisson-receiving openingsin said pontoon by means which transmits a downward force from saidpontoon to said sleeve member and which does not transmit an upwardforce from said pontoon to said sleeve member, said sleeve member beinglowered with said pontoon until at least a portion of said pontoonengages underwater bottom, inserting a caisson through said sleevemember and forcing the lower end of said caisson into theunderwater-"bottom until said lower end has penetrated a sufficientdistance into said bottom to provide a substantial support for saidpontoon, terminating said caisson at a point within said sleeve memberand cementing said caisson into the underwater bottom from within saidcaisson, filling the annular space between said caisson and said sleevemember with cementitious material to permit the load of said foundationpontoon to be transmitted to said caisson through said sleeve member,said means permitting said pontoon to be lifted off said sleeve memberwhen .said sleeve member is cemented to said caisson.

2. The method of establishing a support caisson in an underwater bottomfor detachably supporting a foundation member which comprises the stepsof detach-ably positioning a sleeve member through which the load ofsaid foundation member is to be supplied to a support caisson within anopening in said foundation member by means which transmits a downwardforce from said foundation member to said sleeve member and which doesnot transmit an upward force from said foundation member to said sleevemember, inserting through said sleeve memher a tubular caisson,excavating through said caisson the underwater bottom to apredeterminable depth to permit said caisson to be lowered thereinto,terminating said caisson at its upper end within said sleeve member,

introducing concrete into said caisson to consolidate the lower endthereof into said underwater bottom, filling said caisson with concreteand continuing said filling thereof until said concrete fills saidsleeve member in cluding the portion above said caisson, to cause a bondto be formed between said sleeve member and said caisson through whichthe load of said foundation member may be applied to said caissonthrough said sleeve member, said means permitting said foundation memberto be lifted off said sleeve member when said sleeve member is bonded tosaid caisson.

3. A support caisson detachably supporting an underwater foundationstructure comprising a caisson member extending downwardly into landsubmerged under a body of water, a sleeve member surrounding saidcaisson adjacent the upper end thereof and in annular spacedrelationship therewith, an integrally affixed collar member extendingradially from the lower end portion of said sleeve member, said sleevemember extending upwardly from the upper end of said caisson, acementit-ious material filling said caisson and the portion of saidsleeve member extending above said caisson and the annular space betweensaid sleeve member and said caisson and fixedly bonding said sleevemember to said caisson, and underwater foundation structure having anopening therein in alignment with and of radially greater dimension thansaid sleeve member and of radially less dimension than said collarmember and receiving said sleeve member in vertically slidabletelescoping relationship to place said foundation structure indetachable load supporting engagement on said collar member, said sleevemember terminating at its upper end within said body of water.

4. A support detachably supporting an underwater foundation structurecomprising an elongated member extending downwardly into and aflixed tothe earth submerged under a body of Water and terminating at its upperend within said body of water, a sleeve member surrounding the top endportion of said elongated member in annular spaced relationshiptherewith and extending upwardly therefrom and terminating at its upperend within said body of water, a cementitious material filling theannular space between and binding together said elongated member andsaid sleeve member, a radially extending collar member affixed to saidsleeve member adjacent the lower end thereof, and an underwaterfoundation structure having an opening therein complementary to saidsleeve member, said opening being proportioned with a radially greaterdimension than said sleeve member and with a radially less dimensionthan said collar member and receiving said sleeve member in detachabletelescoping relationship to place said foundation structure in loadsupporting detachable engagement with said collar member.

References Cited in the file of this patent UNITED STATES PATENTS2,248,051 Armstrong July 8, 1941 2,589,146 Samuelson Mar. 11, 19522,675,680 Emshwiller Apr. 20, 1954 2,775,095 Harris Dec. 2-5, 1956FOREIGN PATENTS 149,137 Great Britain Aug. 12, 1920 OTHER REFERENCESEngineering News Record, Aug. 30, 1951, pp. 41-43.

3. A SUPPORT CAISSON DETACHABLY SUPPORTING AN UNDERWATER FOUNDATIONSTRUCTURE COMPRISING A CAISSON MEMBER EXTENDING DOWNWARDLY INTO LANDSUBMERGED UNDER A BODY OF WATER, A SLEEVE MEMBER SURROUNDING SAIDCAISSON ADJACENT THE UPPER END THEREOF AND IN ANNULAR SPACEDRELATIONSHIP RADIALLY FROM THE LOWER END PORTION OF SAID SLEEVE MEMBER,SAID SLEEVE MEMBER EXTENDING UPWARDLY FROM THE UPPER END OF SAIDCAISSON, A CEMENTITIOUS MATERIAL FILLING SAID CAISSON AND THE PORTION OFSAID SLEEVE MEMBER EXTENDING ABOVE SAID CAISSON AND THE ANNULAR SPACEBETWEEN SAID SLEEVE MEMBER TO SAID CAISSON, AND FIXEDLY BONDING SAIDSLEEVE MEMBER TO SAID CAISSON, AND UNDERWATER FOUNDATION STRUCTUREHAVING AN OPENING THEREIN IN ALIGNMENT WITH AND OF RADIALLY GREATERDIMENSION THAN SAID SLEEVE MEMBER AND OF RADIALLY LESS DIMENSION THANSAID COLLAR MEMBER AND RECEIVING SAID SLEEVE MEMBER IN VERTICALLYSLIDABLE TELESCOPING RELATIONSHIP TO PLACE SAID FOUNDATION STRUCTURE INDETACHABLE LOAD SUPPORTING ENGAGEMENT ON SAID COLLAR MEMBER, SAID SLEEVEMEMBER TERMINATING AT ITS UPPER END WITHIN SAID BODY OF WATER.